1. Field of the Invention
The present invention relates to an aircraft passenger seat frame which is structured to be relatively lightweight, but has an increased strength-to-weight ratio which is capable of withstanding substantial forces, as set by various dynamic and static testing criteria of the Federal Aviation Association (FAA) for aircraft seating.
2. Description of the Related Art
The field of art relating to aircraft passenger seating, and especially custom aircraft seating is very specialized, especially in light of the balance that must be attained between luxury and comfort and the various strict guidelines and requirements which must be met by any design prior to installation into an aircraft. In particular, the FAA is charged with setting forth the various guidelines and requirements which must be met by aircraft components, and in doing so has established a series of dynamic and static tests which test the minimum load or impact requirements of an aircraft component, and an aircraft seat in particular. For example, relevant FAA regulations which the manufacturers of aircraft seats are required to meet are found in FAR 25,562; NAS 809; and AS 8049.
As with many federal safety regulations, it is not until after ratification of new guidelines that the increased safety requirements take affect in the market place. Such is the case with the most recent FAA requirements calling for even greater safety of aircraft components that must first successfully complete testing under substantially greater forces and impacts. For the most part the new FAA regulations are just now beginning to affect manufacturers of aircraft components and consequently, the availability of such products for consumers to choose from.
Specifically, there are presently a number of dynamic tests which an aircraft seat must undergo in order to test various parts of the structural integrity of the seat frame and to determine its safety and viability. One such test involves essentially a simulation of a head-on impact, wherein a substantial amount of force and/or strain is placed on the aircraft seat frame, first on the foundation and base of the aircraft seat, and subsequently, on the seat back portion of the frame as would be the case in a crash situation. The aircraft seat frame must be able to withstand vertical impact forces on its foundation and base, as well as horizontal or buckling forces on the seat back frame itself. The FAA's new requirements have substantially increased the amount of such forces which the aircraft seat frame must withstand during testing.
Presently, most conventional aircraft seat frame designs include generally thick walled metal tubing having rounded or squared configurations. In order to save weight, however, this tubing is generally hollow making it much more susceptible to bending or buckling. In particular, during the various impact tests, the seat foundation and seat base are subject to focused vertical forces which tend to bend the tubing. In order to overcome the increased susceptibility of the tubing to bending, especially under the more stringent FAA testing and safety requirements, prior art seat frame designs seek to increase the wall thickness and/or material thickness of the tubing, and/or seek to add additional tubing reinforcement members. While many of these prior art "solutions" provide sufficient strength to meet safety and testing requirements, there are several drawbacks associated therewith. In particular, and as previously mentioned, the increased cost associated with the use of more material and components is a significant disadvantage to such prior art seat frame designs, but the most significant consideration associated with aircraft design in general has to do with the weight of the components. In particular, most aircraft regulations have some significant size-to-weight requirements for the aircraft, meaning that less seating or cut-backs in other amenities must be implemented to meet the requirements. More importantly, however, for every added pound an aircraft must carry, the fuel consumption of that aircraft increases exponentially. Given the already expensive cost of aircraft fuel, and the many miles and hours lodged by the aircraft, a substantial increase of fuel consumption, not to mention a substantial increases in wear which leads to earlier replacement requirements, significantly increase the up-keep costs of the aircraft. Accordingly, the strength-to-weight ratio can be said to be one of the most important criteria associated with aircraft design and aircraft interior design.
Additionally, aircraft seats are required to undergo what is known as a yaw test wherein the seat is propelled forward to an impact at a certain angle. As a result, when this test is performed, and further due to the use of a shoulder harness on some customized seat designs, a majority of the force of impact on the seat back will be focused at a single upper corner of the seat back and not the overall seat back. Presently, most conventional aircraft seat backs include the rounded or squared steel tubing to comprise the structure of the seat back. Such conventional seat backs, however, upon undergoing the yaw test will translate the majority of the impact through a single side rail of the seat back portion into the seat foundation. While most seat foundations will include a recline cylinder at one side of the seat frame which helps to provide some increased resistance to that force, most existing seat designs leave the side opposite the recline cylinder un-reinforced. Accordingly, if the force of impact in the 10 degree yaw test is directed at an opposing corner from the side at which the recline cylinder is mounted, the un-reinforced side of the seat foundation frame will bear all or most of the impact and is likely to fail. Consequently, seat frames known in the art are now being forced to provide substantially increased strength and/or thicker tubing in the seat foundation and seat back, or are unnecessarily utilizing a second recline cylinder disposed at the previously un-reinforced side of the seat foundation. These designs, however, while providing sufficiently increased impact resistance, also substantially increase the cost of the seat frame in materials and added parts, and more importantly will substantially increase the weight of the aircraft seat frame.
Still another FAA test preformed on aircraft seat frames, which has also recently been increased in severity, involves the buckling or flexing of the underlying support surface. Specifically, in certain crash situations, the underlying support surface or floor of the aircraft to which the seats are secured may tend to buckle, flex or otherwise bend. While this floor is preferably structured to maintain some sort of structural integrity during a crash situation, most conventional floor surfaces will waiver or buckle a substantial amount, partly to dissipate the impact forces and maintain its general, overall integrity. Still, however, the aircraft seat must be rigidly secured to the underlying support surface, thereby making it very susceptible to becoming completely or partially dislodged from the underlying support surface during such testing. As result, and in an attempt to solve the problems associated with such testing, others in the art have turned to larger, bulkier and accordingly, heavier securing structures to mount the seat to the underlying support surface. Such increases, however, can significantly add to the cost and overall weight of the seat, and can sometimes function to lessen the ability of the underlying support surface to maintain its structural integrity during the testing.
Accordingly, there is a substantial need in the art to provide an aircraft seat frame which is capable of meeting the new and increased safety and testing requirements set forth by the FAA, and which at the same time is not substantially more heavy in weight and which does not have a greatly increased cost associated with production nor with the materials needed. As will be appreciated by those skilled in the art, if either the weight of or the cost associated with the aircraft seat frame is increased, it will severely and negatively impact the ability of the aircraft owner to fully equip the aircraft with as many passenger seats as possible and/or with other needed or desired equipment.